Process for producing high bulky yarn by false-twisting system

ABSTRACT

A fibrous strand including at least some short fibers and composed of two or more kinds of fibers of different melting point temperatures is, concurrently with false twisting, and in a vibrating condition, heated by a heater of the non-contact type at temperatures between the highest and lowest melting point temperatures of the component fibers so as to produce spun-like yarns of a substantially twistless configuration containing uniformly scattered points of inter-fiber binding and fibers crimped in the form of a coil.

United States Patent Kitazawa et al.

nu 3,874,160 1 Apr. 1,1975

PROCESS FOR PRODUCING HIGH BULKY YARN BY FALSE-TWISTING SYSTEM lnventors: Shin-lch Kitazawa, Kyoto; Takao Negishi; Kozo Susami, both of Otsu,

all of Japan Assignee: Toray Industries, Inc., Tokyo, Japan Filed: Jan. 14, 1974 Appl. No.: 433,137

Related US. Application Data Division of Ser. No. 239,462, March 30, I972, abandoned.

Foreign Application Priority Data June 17, l97l Japan 4642947 US. Cl. 57/157 TS, 28/62, 28/76 T,

57/34 HS, 57/140 BY, 57/157 R Int. Cl DOZg 1/02, D02g 3/04 Field of Search 57/34 HS, 140 BY, 157 R, 57/l57 TS; 28/62, 76 T [56] Y References Cited UNITED STATES PATENTS 3,067,563 12/1962 Van Dijk 57/34 3.6l6.167 l0/197l Gosden..... 57/140 BY X 3,745,757 7/1973 Selwood 57/I57 R Primary Examiner-John W. Huckert Assistant Examiner-Charles Gorenstein 4 Claims, 8 Drawing Figures PROCESS FOR PRODUCING HIGH BULKY YARN BY FALSE-TWISTING SYSTEM This is a division of application Scr. No. 139.462. filed Mar. 30. 1972. now abandoned.

The present invention relates to a process and apparatus for producing spun-like yarns by a false-twisting system. more particularly this invention relates to a process and apparatus for producing spun-like yarns of substantially twistless configuration from a fibrous strand composed of fibers having different melting point temperatures by the application of heat during the false-twisting operation.

As a technique for producing spun-like yarns. the art of false-twisting of fibrous strands issuing from spinning machines is known to persons skilled in the art. In this connection. the conventional false-twisting processes are roughly classified into two groups.

In the false-twisting process of the first group. a tibrous strand issuing from the spinning machine is composed of a fibrous component having a high meltingpoint temperature and a fibrous component having a low melting-point temperature. In this case. the first mentioned component neither melts nor decomposes at the melting-point temperature of the secondmentioned component. After the issue from the spinning machine. the fibrous strand is subjected to the false-twisting action under heat at temperatures whereat the second-mentioned component melts so as to bind the first-mentioned component fibers to each other. After this false-twisting action under heat. the fibrous strand is wound up in the usual manner in a substantially twistlcss condition.

Although the process of the above-described type has its own merits. it is accompanied by serious drawbacks as hereinafter described. especially in the actual practice of the process. in this process. the lihrous strand is heated during the false-twisting. For this purpose. especially when a fibrous strand of a relatively large thickness has to be processed at high speed. it is necessary to provide a long heater surface. Further. for high efficiency in the heating. the fibrous strand is generally processed while in direct contact with the heater surface during the heating. The thicker the fibrous strand. the longer the heater surface. This direct running contact of the fibrous strand with the long heater surface considerably hinders the smooth propagation of the twists along the fibrous strand and the twists imparted by the false-twisting spindle do not smoothly develop to the strand portion near the front rollers nip. This poor twist impartation results in the fibrous strand in a less twisted disposition which then comes into running contact with the heater surface and the fibrous component of the low melting point temperature tends to adhere to the heater surface in a fused condition. The above-mentioned poor twist impartation and thermal fusion of the fibrous material to the heater surface tends to cause frequent breakages of the fibrous strand during the processing and. partly due to such hreakages of the strand. the quality of the yarn produced is considerably degraded.

In the case of the false-twisting process of the second group. adhesive agents in the liquid state are applied to the fibrous strand concurrently with the false-twisting action and the adhesive agents are solidified by a subsequent heating action before the winding up action in the usual way.

This process also is accompanied by drawbacks as hereinafter described. Because the adhesive agent or agents are brought into contact with the fibrous strand in the liquid state. the solvent or solvents used must be removed front the strand in a later stage of the operation and such essential removal of the solvent requires corresponding provision of arrangementls) for such a removal. Further. the necessary drying of the adhesive agentts) tends to limit the processing speed of the strand so treated. in the process of this type. the heating must be performed without direct contact of the fibrous strand with the heater surface. Such indirect heating causes lowering of the heating efficiency and troublesome handling of the strand during the processing. When the adhesive agenttsl are applied to the strand in the liquid the binding of the component fibers takes place along the entire length of the fibers resulting in increased restriction of the free movement of the component fibers in the end products. Such restricted movement of the component fibers brings about a degraded appearance. poor hand and poor stretchability of the products obtained.

The object of the present invention is to provide a process and apparatus for producing spun-like yarn of a substantially twistless configuration but having excellent coherency by a false-twisting system while eliminating the drawbacks encountered in the prior art of similar systems.

in the art of the present invention. first a fibrous strand containing at least some short fibers is prepared from two or more kinds of fibers having different melting point temperatures. The fibrous strand so prepared is processed through a heater of the non-contact type in a vibrating condition before arrival at the falsetwisting spindle. which heater has a heater surface spacedly facing the running fibrous strand and has a temperature between the highest and the lowest melting point temperatures of the component fibers.

Further features and advantages of the present invention will be made clear in the following description, reference being made to the accompanying drawings. wherein.

FIG. I is a schematic sketch of one embodiment of the apparatus of the present invention.

FIG. 2 is a schematic sketch of another embodiment of the apparatus of the present invention.

FIGS. 3A to 3D are schematic sketches for showing various transverse profiles of the heater surface of the heater used in the apparatus of the present invention.

FIGS. 4 and 5 are schematic sketches for explaining the dimension of the heater surface of the heater used in the apparatus of the present invention.

Referring to FIG. 1. an embodiment of the arrangement for carrying out the method of the present invention is illustrated. In the arrangement. a roving l which is made up of fibers of different melting point temperaturcs and including. at least some short fibers is fed to a draft zone 2 from a supply bobbin 3. In the case of the example shown. a draft zone of the so-called three lines type including apron rollers is used. After completion of the drafting. the drafted fibrous strand 4 is advanced through a heater 6 of the non-contact type and is false twisted by a false-twisting spindle 7. Subsequent to the false-twisting, the fibrous strand 4 is taken up by takeup rollers 8 and wound on a take-up package 9. The fibrous strand 4 is advanced through the heater 6 in a vibrating condition. the vibration being caused by the ballooning due to the high speed false-twisting action of the spindle 7.

Another embodiment of the arrangement for carry ing out the method of the present invention is illustrated in l-'l(i. 2. wherein a multifilamentary yarn ll from a supply bobbin [2 is consolidated with a sliver 13 of spun fibers front a separate supply bobbin l4 when they are introduced into a draft zone 16 ofthe so-ealled two lines type. The spun fibers composing the sliver l3 are different from the filaments composing the yarn l I in the melting point temperature. After drafting. the consolidated fibrous strand 17 is heated by the heater 6. false twisted by the spindle 7. taken up by the takeup rollers 8 and wound up onto the take-up package 9. During the travel through the heater 6. the fibrous strand 1? is placed in a vibrating disposition due to the ballooning caused by the high speed false-twisting ac tion of the spindle 7.

As briefly mentioned above, the material fibrous strand to be subjected to the process of the present invention should be made up of two or more kinds of fibers of different melting point temperatures and. further. should contain. at least partly. a certain amount of short fibers such as spun fibers. Such fibers as polyesters. polyamides. polypropylene. rayon. acetate. silk and wool can be used in suitably designed combination. This combination should be so designed that at least one kind of fiber can be given coil-shaped crimps by the false-twisting operation. For example. a combination of polyester fibers containing 5 to 20 percent by weight of polypropylene fibers is favourably used in the process of the present invention. the heating temperature by the heater 6 ranging from l ltl to l8tlC That is. the heating is carried out at temperatures so that no melting of the polyester fibers takes place.

It is also necessary that the material fibrous strand should contain at least some short fibers. For example. the material fibrous strand may be composed of two or more kinds of short fibers of different melting point temperatures. The fibrous strand may be provided in the form of a filamentary yarn or yarns doubled with one or more short fiber strands. the melting point temperature of the former being different from that of the latter. Further. filamentary yarns of different melting point temperatures may be combined with one or more short fiber strands.

The material fibrous strand so prepared must be subjected to heating by the heater 6 of the non-contact type. This heating must he carried out at temperatures so that at least one kind of fibers of low melting point temperature melt but the fibers of the highest melting point temperature do not melt at all. By the melting of the fibers of low melting point temperaturcts), the remaining non-melted fibers are bound to each other at random points. This binding by melting takes place uniformly at every point of contact within the configuration ofthe material fibrous strand resulting in the build ing of uniformly scattered points of inter-fiber binding. Owing to the presence of such inter-fiber binding points. the yarn so produced is provided with a desir' able bulkiness caused by the false-twisting together with stable internal configuration caused by this binding by melting.

For the heating of the fibrous strand according to the present invention. a heater 6 of the non-contact type is used. This non-contact type heater is desirably so constructed that the heater surface spacedly surrounds the (ill running fibrous strand so that the strand is uniformly heated from outside. In this sense. an internally hollow heater is desirably used for the heating purpose. Because the strand does not contact the heater surface ditectl). the heater surface is not soiled by the molten fibers of low melting point temperaturets) and the falling of fibers from their associated fibrous strand can be minimized. Further. non contact of the fibrous strand with the heater surface assures enhanced development of the twists along the strand during the false-twisting operation. A further detailed explanation of the design of such heater will be given in the later part ofthis specification.

It is another important feature of the present inven tion that the fibrous strand passes through the heater in a vibrating condition. Provision of such vibration to the fibrous strand is effected by utilizing the ballooning of the strand caused by the high speed false-twisting action of the spindle 7 or by equipping the heater with a suitable vibrator mechanism for compulsively vibrating the fibrous strand. such mechanism being located near the inlet or outlet terminal of the heater 6. The fibrous strand may be vibrated either vertically or horizontally. lf ballooning is utilized for this purpose. false-twist spindles of relatively large diameter are desirably used so as to result in the ballooning of larger extent.

After heating. the strand is successively subjected to the falsetwisting operation, which is carried out using conventional spindles of the peg-type, friction type or pneumatic vortex type. Among these. spindles of the inside contact type and pneumatic vortex type are desirably employed.

In the case of the conventional false-twisting operation. the fibrous strand is usually overfed into the falsetwist zone. In contrast. the fibrous strand is somewhat underfed into the false-twist zone according to the present invention. This is because. when a fibrous strand of rather thick construction such as a roving is directly subjected to the false-twisting as in the case of the present invention, the conventional overfccd system results in insufficient irnpartation of twists due to lowering of the strand tension and such poor twist impartation induces frequent brcakagcs of the strand during the processing.

Experiments were carried out by the inventors of the present invention for determination of the optimum strand feed rates into the false-twisting zone and the results so obtained are shown in Table 1 below. the feed rate being given in the form of the ratio of the surface speed V, of the feed rollers to the surface speed V,, of the delivery rollers of the false twist zone.

From these results. it is deduced that the feed rate of the fibrous strand into the false-twisting zone in the present invention is desirably in a range from (1.88 to I .00.

As already described. a heater of the non-contact type is used for heating of the fibrous strand in the present invention and such heater is desirably so constructed that the heater surface spacedly surrounds the running fibrous strand so that the strand is uniformly heated from the outside. i.e. a hollow heater is desirably used in the present invention. In other words. the heater surface is desirably provided in the form of a heating tunnel through the heater body. the internal wall surface of the heating tunnel forming the heater surface which spacedly encircles the fibrous strand in such a disposition so that. when the transverse cross sectional profile of the heating tunnel is considered. the path of the fibrous strand coincides substantially with the center of the profile. Some examples of the tunnel profile are shown in FIGS. 3A to 3D, i.e.. the profile may be round as shown in FIG. 3A. elliptical as shown in FIG. 3B, oblong as shown in FIG. 3C or rectangular as shown in FIG. 3D. In the case where the strand vibrates due to ballooning. the profile shown in FIG. 3A is advantageous whereas. when the strand vibrates horizontally. the profiles shown in FIGS. 38 to 30 are advantageously employed. Vertically elongated modifictb tions of the profiles shown in FIGS. 38 to 3D are desirably adopted when the strand vibrates vertically. That is. various modifications of the profile can be utilized in accordance with the processing condition of the strand during the heating operation.

In order to fix the optimum dimensions of the heating tunnel. an imaginary inscribed circle P of the tunnel profile is considered as shown in FIG. 4 with its center 0 coinciding with the designed path of the fibrous strand. The dimensions of the heating tunnel were considered in terms of the diameter of this circle P by the inventors of the present invention.

In the experiment, polyethylene-terephthalate staple fibers of 2 denier fineness and 51 mm length were used as the first component. Staple fibers of 2 denier tineness and St mm length made up of a copolymer compound of 80 percent by weight of polyethyleneterephthalate and 20 percent by weight of polyethylene-adipate were used as the second component. An ordinary blended roving of one-third grams per meter thickness was spun from 9!) percent by weight of the first component and It) percent by weight of the second component. The roving so obtained was processed through the arrangement shown in FIG. I under the following processing conditions.

Draft ratio: It] Spindle rotation; S Ill RPM Surface speed of the front drafl rollers 5.0 X ltl MIM The results obtained by changing the diameter of the circle P are shown in Table 2 below.

Table 2 Diameter of the Variation in Strand breakage per Table Z-Continued \arialion in strength Diameter of the circle P in nnn Strand breakage pel ltllltl spindles per hour 13 Z-t ll till From this result. it was confirmed that the strand breakage increases when the diameter of the circle P becomes smaller than It) unit. This is considered to be caused by the accidental contact of the running fibrous strand with the heating tunnel internal wall. Further. there is a considerable increase in the variation in the yarn tensile strength when the diameter of the circle exceeds 50 mm. This is considered to be caused by the poor heating effect of the heating tunnel wall which is too far from the running fibrous strand. From this analysis, it is considered that the diameter of the circle P lies desirably in a range from 12 to 50 mm.

As already described the heater used in the present invention is desirably provided with a heating tunnel whose internal wall spacedly encircles the fibrous strand passing therethrough. However. from the viewpoint of the yarn (fibrous strand) handling by the operators during the process. it is desirable that the heater is provided with a longitudinal slit which communicates the interior of the heating tunnel with the outside. If the heater is provided with such a longitudinal slit, the yarn can be easily handled from the outside by the operators at the time of a malfunction such as a yarn breakage. However. when considered from the viewpoint of the heating effect of the heater. it is desirable that the dimensions of such a longitudinal slit should be minimized as far as possible in order to prevent the possible invasion of the external atmosphere.

So as to fix the optimum dimension of the longitudinal slit. the imaginary inscribed circle P used in relation to the tunnel profile 0 (see FIG. 4) is used also, reference being made to FIG. 5. In the illustrated structure, the heater is provided with a longitudinal slit IS on one side thereof. An included angle 0 between lines eonnccting the upper and lower fringes 18a. 18b of the slit 18 with the yarn path R is considered as an index of the slit dimension and is hereinafter referred to as the slit center angle."

Experiments similar to that employed in the determination of the optimum heating tunnel dimensions were carried out by the inventors of the present invention, wherein the diameter of the circle was selected at 20 mm and the value ofthe slit center angle 6 was varied.

The experimental results so obtained are shown in Table 3 below. It is widely known to persons skilled in the art that. in the actual use of the yarns. the employable value of the variation in the yarn strength should be (H7 or smaller. From this point of view. it is concluded that the adoptable value of the slit center angle 6 is 90 or less.

Table 3 Slit center angle I! in degrees arialion |n strenglh Isl) 0,2231) I5!) 0.232 I20 0.: l a an t). I no no 0. l 53 in (M55 See l'able I As already explained. vibration of the fibrous strand in the present invention is most simply realized by making use of the ballooning thereof caused by the falsetwisting action. in this case. ballooning of the strand generates a vortex pneumatic flow within the heating tunnel resulting in a uniform heating effect on the librous strand. Further. due to the centrifugal force of As is clear from these results. no rich thermal binding effect can be expected when the ballooning diameter is below l mm whereas an increase in the yarn breakage is observed when the diameter exceeds 20 mm. Further. when we consider the fact that the actually acceptable yarn strength, which is the product of the yarn count and the single yarn strength. should be larger than 8.000 gr and the fact that the industrially allowable yarn breakages should be less than 50. it is consid ered that the desirable employ-able ballooning diameter is in a range of from 2 to 20 mm.

A method for obtaining the ballooning diameter in the above-determined range will hereinafter be described in detail. For this purpose, a series of experiments were conducted by the inventors of the present invention and the results obtained thereby are shown in Table 5 below.

Table 5 Material Ballooning diameter in mm ning speed MPM Y arn Void count ratio Feed ratio Twists in TPM C rise Tetron staple (2 d x 51 mm) Copolymerized Tetron staple Blend ratio Tetron staple (3 d X 8) mm) Copolymerized 'letron staple Blend ratio l 5% ditto ditto 'letron staple (L5 d X 44 mm) Copolymerizcd Tetron staple (L5 d x 44 mm) Blend ratio This value was obtained in the following manner:

the ballooning, the air contained in the core part of the strand configuration is forced out therefrom resulting in increased binding of fibers by melt fusing. In this connection. the influence of the ballooning diameter on the yarn strength and the yarn breakage was experimentally confirmed by the inventors of the present invention. The experiment was conducted in the same manner as that in the determination of the heating tunnel dimensions. The diameter of the circle P was selected at mm and the heating temperature was 225C. The results so obtained are shown in Table 4 below.

Table 4 D: Apparent cross sectional area of the yarn. n; Number of l'iheni per the area. d; Average cross sectional area of individual fibers.

From this analysis, it was confirmed that the desirable ballooning diameter can be obtained when the twist is in a range from 50 VFlto I50 m (N; metric system count). the feed ratio is in a range from 0.88 to l .00 and the void ratio is in a range from 0. l 5 to 0.50.

The following examples are illustrative of the present invention. but are not to be construed as limiting same.

EXAMPLE I Polyethylene-terephthalate staple fibers of 2 denier fineness and 5| mm length were prepared (the first component). Staple fibers of 2 denier fineness and 5l mm length were prepared from a copolymer composed of R percent by weight of polyethylene-terephthalate and 20 percent by weight of polyethylene-adipate (the second component). A blended roving was produced from 90 percent by eight of the first component libers and 10 percent by weight of the second component fibers. This roving was processed through the arrangement shown in Fl(i. I. wherein the draft ratio was 20. the diameter of the circle P was mm. the length of the heater was I cm. the heater was heated at the temperature of ZIPC and the remaining conditions were adjusted as in case No. l in fable 5. From the process so conducted. the following meritorious features were observed by the inventors regarding the art of the present invention.

1. The yarn so produced possessed desirable bulkiness and stretchahility. each componental fibers having coil-shaped crimps Despite its substantially non-twisted configuration. the yarn so produced possessed sufficient strength.

3. The fibrous strand could be processed at very high processing speed.

4. There was no need to positively recollect the solvents.

. The yarn so produced was provided with a span yarn like hand. resulting in the production of fabrics therefrom having a soft hand. crisp touch and a strong resistance against pill formation.

A more detailed explanation will hereinafter he made as to the above-recited meritorious feature (5) of the art of the present invention.

As a measure for enhancing the resistance ofthe fabric against pill formation. it is conventional to bind componental fibers of the yarn by melting some of the componental fibers. However. when the internal configuration of the yarn is almost full of the molten substance. the resultant hand and touch of the fabrics made up of such yarns are unsuitable for wearing use. In order to obviate such trouble. the technique was devclopcd of binding componental fibers to each other at points uniformly scattered within the yarn configuration by thermal melting of some componental fibers, i.e.. to build uniformly scattered points of inter-fiber binding by thermal melting of some componental fibers in the yarn configuration. However. in the case of the conventional processes of this sort. the polymeric ori entation of the fibers tends to be badly disturbed by the thermal melting phenomenon resulting in considerable lowering of the yarn strength.

From this analysis of the conventional techniques, the inventors of the present invention have confirmed that. in order to obtain the yarns accompanied with the above-described meritorious feature (5 the yarn must be of a substantially twistless configuration and the componental fibers must he melt fused to each other to a prescribed extent. in this connection, the inventors have used a value L called the melt-fusion index" as a measure for designating the extent of the thermal fusion of the fibers composing the yarn. It was confirmed by the inventors of the present invention that the meltfusion index should desirably be in a range from 0.02 to 0.40.

Determination of the value of this melt-fusion indev L is carried out in the following manner.

The specimen is immersed in a mixed solution of paraffin and ethylene cellulose. .-\fter solidification of the paraffin. extremely thin laminae are formed by slicing the solidified body in a direction perpendicular to the longitudinal direction of the specimen yarn. By using an optical microscope. the number NM of the fibers in the cross section is counted. in this case. when two or more fibers are melt-fused together forming a single continuous body. the body is counted as a liber. Further. the converted cross sectional area is designated as ST and the average cross sectional area of a fiber before melt fusion is designated as S0. The converted cross sectional area ST is equal to SM X I'llu. where I is the mean tensile strength of the yarn. This is the mean value of 50 measurements taken on an Instron tensile tester with a test length of 0.5 cm and an elongation rate ot'0.5 cm/min. lo is the mean tensile strength of the yarn obtained in a similar way but after melt fusion. L' sing the above-defined values. the melt-fusion index I. is calculated as follows;

It will be understood that the valve ST/Sn corresponds to the number of fibers per cross section if no amalgamation by melt fusion takes place. When there is no actual melt fusion. NM is nearly equal to ST/Su and. accordingly. I. is nearly equal to zero.

The value of the melt fusion index I. is greatly intluenced by the processing conditions in the production of the yarn. For example. when the percent blend of the fibers of the lower melting point temperature is IS. the heating time is 30 minutes and the heating is carried out at a temperature higher by l0C than the melting point temperature of the fibers of the lower melting point temperature. the resultant value of I. is 0.5 l The fabrics made up of yarns of such melt-fusion index possess undesirable hand and touch. When the heating is carried out at temperatures near the melting point of the major componental fibers. the resultant value of L is in most cases 0.02 or smaller and the produced fabrics possesses very poor hand and touch. A similar result is obtained when the percent blend of the fibers of the lower melting point temperature is 2 or less.

EXAMPLE 2 Polyethylene-terephthalatc staple fibers of 2 denier fineness and 51 mm length were prepared (the first component). Staple fibers of 2 denier and SI mm length were prepared from a copolymer of 2 l 2C melting point temperature composed of polyethyleneterephthalate and 20 mol percent of isophthalic acid (the second component). Further, rayon staple fibers of 2 denier fineness and SI mm length were prepared (the third component). The three components were blended in a ratio of 514:! so as to produce a roving of 77 grain thickness on the usual spinning system. The roving so prepared was processed through the arrangement shown in FIG. 1. wherein the draft ratio was l8. the number of the false twists was 800 TPM. the heating temperature was 230C and the take-up speed was 20 MPM. The resultant value of L of the yarn so produced was 0.045 and a in en fabric of 70 (3K densities made thereof had desirable hand. escellent crisp ness and enhanced resistance against pill formation ((irade 4. lCl-method l Hr).

[EXAMPLF 3 Polycth lenc-terephthalate staple fibers of I. denier fineness and SI mm length were prepared (the first component). Staple fibers of Z denier fineness and 51 mm length were prepared from a copolymer of 234C m.p. temperature composed of mo] percent of isophthalic acid and polyethylenederephthalate (the second component). A common type of sliver having a thickness of one-half gram per meter was produced from parts by weight of the first component and l part by weight of the second component. Separately from this. a polyethyleneterephthalate multifilamentary yarn of 75 denier containing 36 filaments was prepared. The sliver and the multifilamentary yarn so prepared were processed in the arrangement shown in Fl(i. 2. wherein the draft ratio was In. the number of the false twists was 620 TPM. the heater was kept at 240C. the length of the heating zone was l.' nt and the yarn take-up speed was I52 MPM.

The yarn so produced possessed soft hand and good crispness. with a meltfusion index L of 0.06. A plain knitted fabric thereof had a desirable hand and enhanced resistance agaisnt pill formation (Grade 4. lCl method 5 Hr).

EXAMPLE 4 A worsted roving of one-third gram per meter was prepared from acrylic staple fibers of 3 d fineness and 8 mm length. Separately from this. a nylon 6 multifilamentary yarn of denier containing l0 filaments was doubled with a multi-filamentary yarn of 20 denier containing 7 filaments. the latter being made up of a copolymer composed of 70 percent of nylon 6 and percent of nylon l2. Both the roving and the doubled multi-tilamentary yarn were processed in the arrangement shown in FIG. 2 wherein the draft ratio was 20, the false-twisting spindle was rotated at a speed of l 31,000 RPM. the diameter of the circle P of the heater was 18 mm. the heating temperature was 150C and the yarn processing speed was 98 MPM. The yarn so produced had excellent hand with a melt-fusion index of 0.25.

EXAMPLE 5 Side-by-side type composite staple fibers of 3 denier fineness and 76 mm length were prepared from polyethylene-terephthalate and a polyethylenetcrephthalate copolymer containing l0 mol percent of isophthalic acid (the first component). Polyethyleneterephthalate staple fibers of 3 denier fineness and 76 mm length were prepared also (the second component). A sliver of one-half gram per meter thickness was produced from 3 parts by weight of the first component and l part by weight of the second component. The sliver so produced was processed in the arrangement shown in FIG. I under conditions the same as those in Example l. A woven fabric was produced from the yarns so produced. the value of L being 0.37. The fabric had a soft hand and rich crispness. with a resistance against pill formation ofGrade 5 (lCl-method l0 Hr).

The number of the false twists to be imparted to the fibrous strand in the present invention must be suitably selected in consideration of the hulkiness and/or stretchahilit required for the yarn produced. thickness and composition of the fibrous strand to be processed and content of the fibers of low m.p. temperature. The smaller the number of the false twists. the poorer the bulkiness and the stretchability. Use of a thermoplastic filamentary yarn in combination with optimum number of the false twists results in a yarn having excellent stretchability and recovery from torque. in the case where non-thermoplastic filamentary yarns or yarns already thermally treated at temperatures higher than the false-twisting temperature are used. yarns having poor stretchability but rich bulkiness are obtainable. Further, in the system shown in FIG. 2. the sliver 13 may be supplied in an intermittent mode.

ln case the fibrous strand to be processed is composed of short fibers only. it is desirable that. in the arrangement shown in FIG. I, the distance between the untwisting point and the nip by the take-up rollers 8 in shorter than the average length of the fibers composing the fibrous strand.

A process for producing knitted or woven fabrics from the yarn produced according to the present invention will hereinafter be briefly described.

Blending of the material fibers must be carefully designed in consideration of the treatments to be applied to the fabric in the later production stages. For exam ple. when polyamide fibers of different melting point temperatures are blended together and the fabric is treated later on with solvents of phenol type. all fibers composing the fabric are melted away by the treatment.

EXAMPLE 6 Polyethylene-terephthalate staple fibers of 3 denier fineness and 89 mm length were prepared (the first component). Staple fibers of 2 denier fineness and 89 mm length were prepared from a eopolymer containing percent of polyethylene-terephthalate and 20 percent of polyethylene-iso-phthalate (the second component). A worsted roving of one-third gram per meter thickness was prepared from 95 percent by weight of the first component and 5 percent by weight of the second component. The roving so prepared was processed in the arrangement shown in HO. 1, wherein the draft ratio was 20. After steaming the yarns so obtained at l00C for 20 minutes. the yarn so prepared were woven into a fabric of'-)2 X densities. After setting in a grey state. the fabric was treated in a dioxane bath at C for 20 minutes so as to remove the low m.p. temperature component by melting. The fabric so obtained possessed a velvet-like soft hand, bulkiness, resiliency and an elegant touch.

EXAMPLE 7 Spun yarns obtained in Example 6 were doubled together. provided with twist of 200 TPM in the direction opposite to the false twisting direction and treated by pressured steam at l05C for setting. A fabric woven from the yarns so prepared was treated in a water solution of formic acid at 40C for 20 minutes for removal of poly-e-caprolactam. The fabric so obtained had a wool-like hand, comfortable touch. softness and resilience.

EXAMPLE 8 Polyethylene staple fibers of 3 denier fineness and 89 mm length were prepared (the first component). Polyethylene staple fibers of 3 denier fineness and 87 mm length having the mp. temperature of 120C were prepared from a copolymer containing 10 parts of polyethylcne-iso-phthalate and it parts of polyethyleneterephthalate (the second component it A worsted roying one-third gram per meter thickness was prepared from 93 percent of the first component and 7 percent ofthe second component. Separately from this. a polyester multifilamentary yarn of 40 denier thickness containing 24 filaments was prepared.

They were both processed in an arrangement substantially equal to that shown in H0. 2. But in this case. only the roving was drafted at a draft ratio of 25 and the multifilamentary yarn was amalgamated with the roying at a position just upstream of the front rollers of the draft zone. The false-twisting spindle was rotated at a speed of l40,000 RPM, the strand was fed at a speed of lSZ MPM, the temperature of the heater was 235C and the heating zone was 1.2 m long. A double jersey fabric, which was made of yarns so prepared. was treated in the dioxanc hath at 80C for 20 min for removal of the low m.p. temperature component. The fabric so produced possessed desirable bulkiness, softness. uniform loop structure and an elegant touch and appearance.

The sul'istantially twistless configuration of the yarn manufactured according to the present invention is desirably utiliyed in the production of pile fabrics which possess excellent covering effect and resilience against compression. in accordance with the requirement of the end Lise, only the point portion of the piles may be removed by melting in the later treatment of the pile fabrics, This removal may also be performed by mechanically shearing the point portions of the piles.

EXAMPLE 9 Polyacrylonitrile staple fibers of It) denier fineness and 76 mm length were prepared (the first component). Staple fibers of 7 denier fineness and 76 mm length were prepared from a eopolymer containing 45 mol percent of nylon 6, 10 mol percent of nylon 66 and 45 mol percent of nylon l2 (the second component). A worsted roving of 4 g/m thickness was prepared from )5 percent by weight of the first component and 5 percent by weight of the second component.

The roving so prepared was processed in the arrangement shown in FIG. I, wherein the draft ratio was 20, the spindle was rotated at 4400 RPM. the heater was kept at l80C, the heating zone was 1.5 m long and the strand was fed to the heater at a speed of 20 MPM.

Three substantially twistless yarns so produced were doubled together and twisted at I20 TPM and a fabric of the yarns so twisted was produced. Tufting was applied to the fabric on a tufting machine of five thirtyseconds gauge and stitches per 1 inch so as to develop piles of 7 mm height. The tufted fabric was coated on its reverse side with ordinary latex and, after drying. treated in a 70 percent formic acid bath for It) min. for removal of the low m.p. temperature component. The velvet thus obtained had a good covering effect and resilience against compression.

It is also possible in the present invention fora third component to be added to the composition of the material fibrous strand. For example, the material fibrous strand may be composed of the first component A, the second component B which melts at temperatures whereat the first component A is not melted. and the third component C which melts at temperatures whercat the first component A does not melt and is dissolved by a solvent which does not fully melt the first and second components A. B. in this case. the strand is heated firstly so as to cause the melting of the second component B and melting of at least some of the third component C. Secondly. in the fabric state. the third component C is at least partly removed from the fabric by treatment with the aboveanentioned solvent. B the presence of the third component C. the yarn is provided with a strongly bound configuration during the processes preceding the removal of same and. after the removal of same by dissolution. the end product fabric possesses desirable hand and crispness.

EXAMPLE l0 Polyethylene-terephthalate staple fibers of 3 denier fineness and 89 mm length were prepared (the first component). Staple fibers of 3 denier fineness and 89 mm length were prepared by blend spinning of parts of polyethylene-terephthalate with 1 part of polyethylene-glycol (the second component). Polyethylenesebacate staple fibers of 3 denier fineness and R9 nun length were prepared also (the third component)v A worsted roving of one-half gram per meter thickness was prepared front 65 percent by weight of the first component. 15 percent by weight of the second component and 20 percent by weight of the third component. The roving so prepared was processed in the arrangement shown in FIG. I. wherein the draft ratio was 15, the spindle was rotated at 45,000 RPM, the heater was kept at 235C and the yarn processing speed was 28 MPM. The yarn so produced had a strength of 2.5 gram per denier. A plain fabric of 55 X 50 densities was woven using the yarns. This fabric was treated in a 5 percent NaOH bath at 98C for 1 hr. The resultant fabric had an elegant luster, soft hand and bulkincss.

What we claim is:

I. A process for producing spun-like yarns by a falsetwisting system comprising, in combination, forming a fibrous strand from at least two kinds of fibers having different melting point temperatures including adding to the fibrous strand a kind of fibers having a melting point temperature lower than a given temperature and which is dissolvable by a solvent that does not fully dissolve the fibers of the highest melting point temperature of said fibrous strand, said fibrous strand containing at least some short fibers, concurrently falsetwisting, vibrating and heating said strand at said given temperature. said given temperature being between the highest and lowest melting point temperatures of said fibers, carrying out said step of heating without direct contact bctween said fibrous strand and any heating element, and, following said false twisting, removing at least some of said added kind of fibers by treatment with said solvent.

2. The process of claim 1 wherein the fibrous strand is fed to a false-twisting zone for effecting said step of false-twisting, comprising underfeeding said fibrous strand to said false-twisting zone.

3. The process of claim 2 wherein the feed ratio of said fibrous strand to said false twisting zone is in a range of from 0.88 to L00.

4. The process of claim 1 wherein the number of false twists produced in said step of false twisting is in a range from SON to ISON, wherein N is a metric system count of a yarn produced by said process. 

1. A PROCESS FOR PRODUCING SPUN-LIKE YARNS BY A FALSETWISTING SYSTEM COMPRISING, IN COMBINATION, FORMING A FIBROUS STRAND FROM AT LEAST TWO KINDS OF FIBERS HAVING DIFFERENT MELTING POINT TEMPERATURES INCLUDING ADDING TO THE FIBROUS STRAND A KIND OF FIBERS HAVING A MELTING POINT TEMPERATURE LOWER THAN A GIVEN TEMPERATURE AND WHICH IS DISSOLVABLE BY A SOLVENT THAT DOES NOT FULLY DISSOLVE THE FIBERS OF THE HIGHEST MELTING POINT TEMPERATURE OF SAID FIBROUS STRAND, SAID FIBROUS STRAND CONTAINING AT LEAST SOME SHORT FIBERS, CONSURRENTLY FALSE-TWISTING, VIBRATING AND HEATING SAID STRAND AT SAID GIVEN TEMPERATURE, SAID GIVEN TEMPERATURE BEING BETWEEN THE HIGHEST AND LOWEST MELTING POINT TEMPERATURE OF SAID FIBERS, CARRYING OUT SAID STEP OF HEATING WITHOUT DIRECT CONTACT BETWEEN SAID FIBROUS STRAND AND ANY HEATING ELEMENT, AND, FOLLOWING SAID FALSE TWISTING, REMOVING AT LEAST SOME OF SAID ADDED KIND OF FIBERS BY TREATMENT WITH SAID SOLVENT.
 2. The process of claim 1 wherein the fibrous strand is fed to a false-twisting zone for effecting said step of false-twisting, comprising underfeeding said fibrous strand to said false-twisting zone.
 3. The process of claim 2 wherein the feed ratio of said fibrous strand to said false twisting zone is in a range of from 0.88 to 1.00.
 4. The process of claim 1 wherein the number of false twists produced in said step of false twisting is in a range from 50N to 150N, wherein N is a metric system count of a yarn produced by said process. 